Duane's uniocular micro-tremor or superior oblique myokymia of Hoyt and Keane

Two cases of intermittent unilateral motor disturbance of the superior oblique muslce are presented and compared with cases reported previously by Duane, Clark and Hoyt & Keane and briefly mentioned by Duke-Elder in his System of Ophthalmology. The first case is a girl with longstanding history of oscillopsia, vertical and tortional oscillatory diplopia. No abnormal eye movements were observed but objective evidence of the disturbance was obtained in the form of electromyography during which relationship of the superior oblique was established. In contrast, the second case experienced episodes of static vertical and tortional diplopia similar to the case reported to by Clark. Again the relationship in the condition was unilateral involving the superior oblique muscle. There was no corroboratory evidence to support the diagnosis of an intermittent superior oblique tendon sheath syndrome. Hoyt & Keane's theory based on their electromyography findings that the lesion is in the lower motor neuron unit is reported and the significance of the oscillopsia as corroboratory evidence is discussed.